Vernier for tuning reactances



May 5, 1925.

IG. W. PICKARD ET AL VERNIER FOR TUNING REACTANCES Filed Nov'. 8, 1924,

` 72 ATrCRNEY,

v TIER ProKARD and JOHN ALBERT PRocToR,

Patented May 5, 1925.

UNITED vSTATES PATENT. OFFICE.

GREENLEAF WHITTIER PICKABD, OF NEWTON CENTER, .AND JOHN ALBERT PROCTOR, OF LEXINGTON, AYMASSACHUSETTS, ASSIGNORS TO WIRELESS SPECIALTY APPA- RATUS COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF NEW YORK.

VER-NIER FOR TUNING REACTANCES.

Application filed November To ZZ whom t may concern:

Be 1t known that We, GREENLEAF WHIT- citizens ot' the United States of America, residing, respectively, at 59 Dalton Road, Newton Center, and 21 Parker Street, Lexington, State of Massachusetts, have invented a certain new and useful Vernier for Tuning Reactances, of which the following description, in connection with the accompanying drawings, is a specification.

This invention relates to verniers for electrical tuning devices, particularly those employed in radio communication, and more particularly for variable air radio' tuning condensers. l

The objects of the invention include that of providing a Vernier whose capacity variation per degree of movement is approximately proportional to the main condenser capacity.

The invention consists ofthe constructions and arrangements described herein and illustrated, by way of'example, in the drawing, which is a perspective and somewhat diagrammatic View of an embodiment of the invention. Prior verniers have had the defect that at the low capacity end of the main condenser scale, the Vernier adjustment is not fine enough relative to the main condenser; while at the high capacity end of the main scale. the Vernier adjustment is too fine, i. e., the entire scale of the Vernier is not enbugh. l

In the drawing, the main condenser is shown at the right, as comprising a rotatable spindle S carrying at its right-hand end an operating handle p and a pointer CI operating over a suitable scale not shown. Spindle S\ carries the movable condenser plates MP, Which are rotated by the spindle. Between said movable plates are located the fixed plates FP of the condenser; the successive plates being separated from one another by air as the dielectric.

At the left is shown the Vernier shaft VS, carrying at its right end a Vernier handle VH and a pointer VI operating over a suitable scale, which may or may not be the same scale over which operates pointer CI of the main condenser.

On the left end of s indle S is mounted 'a eondenser plate CP. n the left end of Ver- 8, 1924. Serial No. 748,552.

nier spindle VS is mounted a condenser are separated from one another by an air lspace constituting a condenser dielectric.

The capacity of the entire device, including that of the main condenser 'MP-FP, and the capacity' between auxiliary plates CP and'VP, is included in the circuit indicated on the drawing of which the terminals are T1 and T2, lead X extending from spindle S to terminal T1 ing fromspindle VS to terminal T2.,

The invention involves the relation between condenser plates CP and VP.

Plate CP is shown as having a certain curvature, so that. when in the position shown (the full capacity of the main condenser being in the circuit, due to the in- -termeshing ot all the plates MP and FP), plate CP offers the greatest opposing snrface to the Vernier plate VP. Thus in the positions of plates CPv and VP shown` the capacity change in thevernier for a given movement of Vernier handle MH is a maximum, i. e., the largest .change for a given movement of handle VH. Conversely, when the capacity of themain condenser is at a minimum (as when plates MP are turned entirely out of mesh with fixed plates FP), then plate CP also will have been so rotated as to present minimumopposing surface to Vern-ier plate VP. Thus any adjusting movement produce a minimum variation of capacity in Vthe circuit T1, T2.

Thus the invention provides' a Vernier having a. capacity Variation per degree 'of movement which is approximately proportional to the capacity of the main variable condenser at any condition` of the latter.

Preferably, the relation of the curva-tures of plates CP and VP is such that the variation in capacity produced by operation ot Vernier handle VH is the same percentage of the capacity of the main condenser at any setting of main condenser handle MH.

The invention may take Various forms. In the embodiment shown, plate CP is more or less disk-shaped and is mounted eccentrically on main spindle S; and vVernier plate VP is formed with a semicircular movable end adjacent to plate CP. That is, plate CP and VP are shaped, at their over-lapping and lead Y extend-` of. VP by handle VH will portions, so as to produce a change of capacity, by movement of Vernier handle VH, which is substantially proportional to the capacity of the main condenser at any of the various settings of the latter as an adjustable device.

If desired, Vernier handle VH and its shaft VS may be concentric with handle MH and shaft S of the main condenser. In that case, of course, plate CP would be insulated from its shaft S, and Vernier plate VP mounted on its shaft VS located concentric with shaft S. Plate CP in such case should be insulated from shaft S, although mounted thereon and rotated thereby, beca-use the concentric structure of shafts S and .VS preferably would result in electrically connecting the two concentric shafts. In this case, plate CP may be eccentrically mounted on shaft S, but plate VP, mounted on shaft VS, is concentric with sha-ft S, thus requiring a change of shape or curvature of either VP or CP or both, as compared with the shapes illustrated in the drawing.-

The invent-ion is not limited to a. Variable condenser with an air dielectric, as shown, for the dielectric may be of solid material such as mica between movable metallic plates. Nor is the invention limited to application to variable condensers, for it may be applied to Variable inductance tuners.

It is to be understood that the invention is not limited to the embodiments and features specifically shown and described herein, but that such embodiments and features are subject to changes and modications with out any departure from the spirit. of the invention.

IVe particularly point out and distinctly claim the part improvement or combination which Weiclaim as our invention or discovery, as followsz l. A Vernier for a rotatable condenser, which comprises an auxiliary 'condenser plate mounted eccentrically on the shaft of the condenser; a rotatable Vernier shaft parallel with the main condenser shaft; and a Vernier condenser pla-te mounted rotatably on the Vernier shaft; the condenser plate on the main condensershaft having a disklike shape, and the condenser plate on the Vernier shaft having an approximately semicircular end adjacent the auxiliary Vplate on the main condenser shaft.

2. A Vernier for a variable tuning condenser', which comprises an auxiliary condenser plate rotatably mounted on the shaft of the main condenser and a Vernier condenser plate co-operating therewith, said ico-operating plate having curvatures of their overlapping portions which cause a change of capacity by operation of the Vernier plate which is substantially proportional to the capacity of the. main condenser a-t any setting of the latter. i

3. A Vernier for a variable tuning reactance, which comprises an auxiliary reactance element controlled by the main reactance, and a. Vernier reactance element co operatingwith said auxiliary element; said co-operating reactances having interrelated portions which, upon movement o-f the Vernier reactance, cause a change which is substantially proportional to the value of the main reactanceat any setting of the latter.

In testimony lwhereof We have signed our names to this specification.

GREENLEAF WHITTIER PICKARD.

JOHN ALBERT PROCTOR. 

